Histopathology and ultrastructure of ovarian hilus cell tumor: Report of two cases

Abstract

Two ovarian hilus cell tumors were studied. One was obtained from a virilized woman, while the other was an asymptomatic incidental finding at surgery performed because of an associated ovarian cyst. The ultrastructural findings were compared with those of the few reported cases in the literature. Comparisons were also made with normal and neoplastic testicular Leydig cells, the homologues of ovarian hilus cells. Intranuclear paracrystalline inclusions were observed in the neoplastic hilus cells of both cases. Complexly structured cytoplasmic crystals were found only in Case 1. A clue to the existence of these particular inclusions was the presence of small eosinophilic masses in corresponding locations in the histologic sections. Neither type of inclusions has been previously described. It is postulated that these and related types of structures are precursors of Reinke crystals. Actual Reinke crystals were not encountered. Prominent cytoplasmic features included vesicular smooth endoplasmic reticulum, frequent large mitochondria with tubular cristae, numerous lipid deposits, membranous whorls, lysosomes, and peroxisomes. Pigment or lipofuscin granules were not observed. Although certain ultrastructural differences existed between the two tumors, they were insufficient to explain why only the patient of Case 1 showed masculinizing effects. The overall histopathology and ultrastructure of ovarian hilus cell tumors are strikingly similar to those of testicular Leydig cell neoplasms.